Study of Seasonal Radiocarbon Variability in the Eastern Tropical Pacific During Periods of Decadal and Interannual Climate Shifts

年代际和年际气候变化期间热带东太平洋季节性放射性碳变化研究

• 批准号: 0551940
• 负责人: Ellen Druffel
• 金额: $ 51.29万
• 依托单位: University of California-Irvine
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-01-01 至 2010-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0551940&HistoricalAwards=false
• 关键词: Study; Seasonal; Radiocarbon; Variability; Eastern

In this project, investigators at the University of California at Irvine will determine the detailed changes of radiocarbon in the surface of the eastern tropical Pacific during distinctive climatic periods in the past 400 years. The researchers expect that these studies will aid in our understanding of how natural variability in climate can influence the ability of the ocean to absorb excess CO2 produced from fossil fuel and biomass burning. High-precision AMS (accelerator mass spectrometry) 14C measurements on seasonal coral bands from the eastern tropical Pacific, located in the "center of action" with respect to El Nino, will be made to determine the variability of the low 14C component of the source waters (presumably Sub-Antarctic Mode Water) from the South Pacific. Three hypotheses will be tested: 1) Wintertime 14C values in Galapagos corals are an indicator for the phase of the PDO; 2) Prolonged periods of winter-time upwelling were present at in the eastern tropical Pacific during the early 1600s and early 1800s, which were likely caused by prolonged entrainment of Sub-Antarctic Mode Water into the Equatorial Under Current; and 3) Wintertime 14C values at Galapagos reveal interannual-to-decadal variability in climate.To test these hypotheses, the following studies will be done: 1) Seasonal 14C and, in collaboration with colleagues at Stanford University, 18O will be measured in Galapagos coral bands that grew from 1900-1996 to determine if the winter-time 14C was significantly lower during recorded periods when the PDO was known to have been in a negative phase (1915-1925 and 1945-1955). A calibration experiment will be performed to demonstrate that the coral species used in this study is indeed recording the entire seasonal signal. 2) Seasonal 14C and 18O measurements of coral bands that grew from 1598-1611 and from 1804-1825 will be made to determine if the winter-time 14C was significantly lower and/or persisted for a longer period of time during these unusual climatic periods. 3) Seasonal 14C measurements will be made of coral bands from time periods that display clear interannual variability in climate (ENSO) and those that are dominated by distinct decadal variability. Collaboration with colleagues at Princeton University is planned to utilize the seasonal 14C records in his ocean circulation modeling experiments designed to calculate variability of past pCO2 and CO2 out-gassing fluxes in the equatorial Pacific.In terms of broader impacts, the project will support the work of one graduate student and two undergraduate students and provide hands-on experience that will prepare them for careers as scientists and educators. The PI is involved with developing outreach activities in conjunction with middle and high school youths. She is also on the advisory board for FCOSEE (Florida Center for Ocean Science Education Excellence COSEE) to assist in developing web-based educational classes at the college level, and participates in teaching a short course on Radiocarbon and the Carbon Cycle every summer.

在该项目中，加利福尼亚大学尔湾分校的调查人员将在过去400年中在独特的气候时期内确定东部热带太平洋表面上的放射性碳的详细变化。 研究人员预计，这些研究将有助于我们理解气候中的自然变异性如何影响海洋吸收因化石燃料和生物质燃烧产生的多余二氧化碳的能力。 将对来自东部热带太平洋的季节性珊瑚带（ACCELERATOR质谱法）进行高精度AMS（加速器质谱法测量），将对El Nino的“行动中心”中的季节性珊瑚带（以EL NINO为单位）确定源水低14c分量的可变性（可能是来自南部太平洋的亚抗抗菌模式）的可变性。 将检验三个假设：1）加拉帕戈斯珊瑚中的冬季14c值是PDO阶段的指标； 2）在1600年代初期和1800年代初，在东部太平洋地区存在冬季上升的时间长时间，这很可能是由于在电流下长时间夹带了亚反抗性模式水进入赤道的延长引起的；和3）加拉帕戈斯群岛的冬季14c值揭示了气候中的年间到十年的变化。要测试这些假设，将完成以下研究：1）季节性14C，并与斯坦福大学的同事合作，将在1900-196频繁确定的Galapagos珊瑚带中衡量18O，以确定在winter Time中的录制量很大，该量很大降低了。负阶段（1915-1925和1945-1955）。 将进行校准实验，以证明本研究中使用的珊瑚物种确实记录了整个季节性信号。 2）将对从1598-1611和1804-1825生长的珊瑚带的季节性14C和18O测量，以确定在这些异常气候期间的冬季14C是否显着较低和/或持续更长的时间。 3）季节性14C测量将是由时间段的珊瑚带进行的，这些时间段显示了气候（ENSO）的年际变化，以及由独特的十年变异性主导的时间段。 计划在他的海洋循环建模实验中与普林斯顿大学的同事合作利用季节性14C记录，旨在计算赤道太平洋中过去的PCO2和CO2外流量的变异性。在更广泛的影响方面，该项目将支持一名研究生和两位学生的教育者，并为他们提供培训者，并为他们提供教育者，并为他们提供教育者的工作。 PI与中学和高中青年一起开发外展活动。 她还是FCOSEE（佛罗里达海洋科学教育中心卓越中心）的顾问委员会，以协助在大学一级开发基于网络的教育课程，并参加每年夏天的放射性碳和碳循环的简短课程。